A modern phone game can cost millions to write, so you'd only really spend that much if you were sure you'd get more back in return. Has the industry reached the stage where it's no longer feasible for the "little guys" to launch a game?

Zero to 21 million users

Topping Candy Crush and Clash of Clans, corks were popping at the Nintendo HQ as Pokémon GO officially became the biggest mobile game (by user count) in US history.

Rocketing to the number one position in all the app stores it appeared in was only the start - within days of its release, Pokémon GO had amassed more daily users than Twitter, earning millions of dollars per day for Nintendo.

The previous number one game was Candy Crush Saga, with 20 million daily active users.

Even more amazing is that it has never been featured in either Apples App Store or Googles Play Store.

And it's not over by a long shot - Pokémon GO now has Snapchat and even Google Maps in its sights.